A ready to run crackerbox.

Introduction

A crackerbox handles just like the name implies, like a square tin being forced to plane on top of rough water. These semi flat-bottom race boats are propelled to incredible speeds with 300+ horsepower V8 engines; a skeg and turn fin being the only things keeping them stuck to the surface. The crackerbox is an ill-handling and challenging hull to race for full-scale and radio controlled drivers alike... and that's what makes them such an exciting class.

Until now, very few electric crackerboxes existed; the class was reserved for large-scale gas racers only. But thanks to Aquacraft and Mr. Grimracer himself (Mike Zaborowski), a brand new electric class has emerged with the introduction of the Aquacraft Gunslinger.

Examining the Gunslinger

As with all Aquacraft boats I've owned, the Gunslinger comes packaged safely and securely. The entire boat is built and ready to run, you'll just need a 3s 2200mAh pack and suitable LiPo charger. Along with the Gunslinger, I received a Great Planes AC/DC 3S LiPo Balancing Smart Charger and a Great Planes ElectriFly LiPo 3S 11.1V 2200mAh pack with a 30c rating.

Constructed of abs plastic, the Gunslinger is 28" long, 10.25" wide, and weighs about 2.3lbs without the LiPo. It comes with a stand to keep it displayed while in dry dock, or in the pits between heats. As I stated in the introduction, the crackerbox is a very unique looking hull; its semi flat-bottom has very little grip on the water, so a plastic-composite skeg is used to keep it tracking straight and to assist in carving through the turns without sliding. The driver figures are located at the aft portion of the hull, and a large dummy V8 engine is molded into the hatch cover.

Under the hull is a plastic-composite 2-blade propeller that's offset slightly to the right to counteract the right-turning tendency of the spinning propeller, known as prop walk. Aquacraft went with a sub-surface drive as apposed to a surface drive, which sacrifices performance and adjustability in favor of scale realism. I personally would have liked to see this boat with an adjustable skegged surface drive.

Hanging off the rear of the transom is a plastic-composite tapered rudder. This unit is designed to break away and pivot back when something strikes it in the water. It works well and has saved me from ordering a new rudder three times (yes, my pond is dirty and filled with sticks).

The hatch attaches in the back with a pair of plastic dowels, and is held down with a locking tab up front; just turn the tab, lift the front of the hatch from the dummy engine, and slide it forward enough to clear the dowels. Be careful not to lift the hatch too high without sliding it forward or you can snap off the dowels.

Like the rest of the Gunslinger, the radio box is made of abs plastic and is fitted with a clear lexan lid that's designed to be taped down with the included waterproof hatch tape. The steering rod exits the box through a rubber cover, which is pretty standard with rc boats. The steering servo is strong enough and quick enough to keep up with the Gunslinger quite well; I never felt like it was lagging behind my controller movements. But with the short distance between the rudder and the transom, it doesn't take much to make this crackerbox turn quickly.

Between the motor and the radio box is the battery mounting deck made of abs plastic and glued to the inside of the hull. A pair of hook-and-loop strips are used to position the battery on the deck, and there's really no chance of the battery coming off unless you plow into a fixed object at full speed... let's hope that never happens. Deans connectors come soldered on the esc.

Metal trim tabs on the transom are the number one method of changing how the boat rides in the water, but unfortunately they are a bit difficult to adjust because they are just 90-degree bent aluminum. In order to successfully adjust the tabs without stripping them right off of the transom, you'll need to unscrew them and either place them in a vice and carefully bend them, or use a pair of adjustable wrenches (or similar) to adjust their angle.

The motor attaches to the propeller shaft with a drive connector. On each end are aluminum fittings with grub screws to secure to the motor shaft and prop shaft. They are connected with a piece of hard rubber to allow of a little movement without damaging the motor or shaft. The prop shaft is routed out the bottom of the hull through a brass tube called a stuffing tube. The shaft must be greased before every session to keep it spinning smoothly inside the tube and to prevent water from traveling up the tube and into the hull.

The motor and esc are both kept cool with water from a pickup on the transom. Forward movement of the Gunslinger pushes water up the pickup and through an aluminum sleeve on the motor, then through the esc's cooling fins, and finally expelled out the left side of the hull.

Setup

Crackerboxes run dirty. They bounce all over the place and can easily flip over if too much air gets under the hull; the big flat bottom acts like a sail if it gets airborne. You have to setup the Gunslinger for racing conditions to keep her planted on the water and not flip. This means losing a little bit of the top speed you would have if the boat was running lose, but gaining much needed stability to keep the wet side pointed down. Since the sub-surface drive isn't adjustable, we're left with the trim tabs as the only adjustment point for tuning how the hull rides in the water (aside from moving the battery location). Remove the trim tabs from the transom and very carefully bend them open a few degrees. We want the tabs to angle down slightly and force the nose of the Gunslinger down on the water just enough to prevent it from flipping backwards at full speed. Turn the hull upside down and look from the bow towards the transom. The tabs should be angled the same on both sides.

The battery location does not affect how the hull rides as much as I thought it would with the Gunslinger. I moved the 3s 2200Mah LiPo from its stock location to in front of the motor, and saw no real change in attitude, speed, or handling. It's safe to say that the stock location will suffice, and the trim tabs should be the main adjustment point.

We want to get every bit of performance out of the Gunslinger with the stock electronics package and without doing any modifications to the hull itself, so replacing the stock plastic prop with a metal one is an easy modification. Aquacraft sells a Grimracer 36x55 metal prop that's designed for the Gunslinger. You will need to sharpen and balance the prop before use. Check out my video on balancing and sharpening a prop below:

Running the Gunslinger

Crackerboxes can be a challenge to drive because they have a wide, semi-flat bottom that rides on top of the water instead of cutting through it like a v-hull. So getting the hull to settle down is the number one priority, or else you'll just end up with an upside down Gunslinger sitting in the middle of the lake. As I stated in the setup section, the trim tabs are really the only tuning point on this hull; angle them down slightly to make the Gunslinger stick to the water. When the water gets rough, the hull will loosen up a bit and gain a little speed without flipping.

I used a GPS from Hobbyking to test the Gunslinger with the stock prop and the Grimracer metal prop. With the stock plastic propeller, I had a top speed of around 21mph. With the Grimracer prop, balanced and sharpened, I had a top speed of 23.6mph. This isn't a FE (fast electric) class of boat by any stretch, but it feels much faster than it's actually going.

Turning is a challenge at high speeds because the hull wants to bounce and can catch the sharp edge of the bottom and flip. This is known as tripping when the hull digs in and rolls in a turn. Some of the larger gas crackerboxes have anti-trip trim tabs that are angled up on the edges to reduce the roll-over tendency of this type of hull, but the Gunslinger doesn't have these. When entering the turn, let off of the throttle a little and ease into the turn, you can easily feel the limits as the hull will begin to bounce if you're going too fast into the turn. Once the Gunslinger begins to exit, you can grab full throttle and power back up to speed. Another way to make a tight turn is to let off the throttle almost completely and turn sharply, applying full throttle again quickly. I demonstrate these turning methods in the running video.

The torque from the motor will cause the hull to lean slightly to the right at full throttle. If the trim tabs are down, it may induce a slight bouncing effect as the hull drops the right side and the tabs bring it back up. Playing with the trim tabs is the best way to reduce this tendency.

Conclusion

The Aquacraft Gunslinger is a unique class of Ready-to-Run boat and makes a great stock racing class as well. It's handling requires some attention on the controls and tuning is needed to get it running fast and level in the water. But don't let that deter you! If you can bend the trim tabs down a few degrees, you can get the Gunslinger into "race trim" and ready to run some hot laps. It's an affordable boat, coming in at under $200, and only requires a 3s 2200mAh LiPo to hit the water running.

If your club is looking to start a new stock class, or you just want something different than the standard issue v-hull or catamaran, I would recommend the Aquacraft Gunslinger.

Nice review. Thanks for the frank assessment of its handling characteristics. I run P limited mono and P mono. While I like the crackerbox design for variety, I don't know if it will hold my interest as a sport boat.

Based on your video, you have tuned out the flat bottomed slap very well. It sure looks faster than 23 MPH. Would it be of further help to fabricate longer trim tabs? What kind of run times are you getting? I imagine that it runs pretty cool, do you think it could handle a four cell pack?

Nice review. Thanks for the frank assessment of its handling characteristics. I run P limited mono and P mono. While I like the crackerbox design for variety, I don't know if it will hold my interest as a sport boat.

Based on your video, you have tuned out the flat bottomed slap very well. It sure looks faster than 23 MPH. Would it be of further help to fabricate longer trim tabs? What kind of run times are you getting? I imagine that it runs pretty cool, do you think it could handle a four cell pack?

Can anyone report on whether it can go in reverse? Seems like controller would allow for it but not sure of esc.

I know this is an old thread, but this boat uses the same [AquaCraft] ESC as the Wildcat EP. Had a WC years ago, the stock ESC is a POS - and no, there's no reverse.

Replaced the AQ ESC with a Seaking 60A (V2) ESC, fit right into the factory ESC holder as though it were made for it. The V2's were disco'ed couple years ago.

Checked the manual, says the motor can pull up to 70A, probably could happen when running "wet". That in mind, I bet one of these would work out quite nicely... https://www.hobbywingdirect.com/prod...ng-120a-v3-esc. The V3's flat bottom will fit perfectly where the stock ESC is outta the box & the extra amp capacity give's overhead when needed. Program box/card not required, but makes things easier, especially if your new to BL setups.

Zoomer-Ron asked about bigger TT's. Based on my experience with the Tower Hobbies Power Vee (repackaged AQ Hammer EP), which also has a wide flat bottom, I feel a set of turn fins would be a better option to improve turning. FWIW: I upgraded it to BL, 2860-2000kv on 3s.

An option that I was thinking of would be to replace the stock trim tabs with a set from the AQ Rio EP... http://www.aquacraftmodels.com/boats...p#product-menu - they're the same size as the one's on the GS27 & have small turn fins integrated. Hole spacing (mounting screws) is the same, so there direct replacements. I would sharpen the leading edge's of the turn fins, fairly thick in stock trim.

I know this is a shot in the dark, but I'll throw it out there. I just got this boat. I ran it for about 3 minutes before the sun went down after I got home from work yesterday. I can tell this a drivers boat, but it's painfully slow. I see the motor can take up to 6s. So I figure I'll upgrade the esc and prop. Need a prop suggestion please.

I know this is a shot in the dark, but I'll throw it out there. I just got this boat. I ran it for about 3 minutes before the sun went down after I got home from work yesterday. I can tell this a drivers boat, but it's painfully slow. I see the motor can take up to 6s. So I figure I'll upgrade the esc and prop. Need a prop suggestion please.

Yeah, it's a submerged drive. The available aftermarket prop for this boat to work with the stock electronics is a 2 blade, 36x55. I was wondering if there were other options. I never ran a submerged drive before. I plan on running it on 5s or 6s depending how silly it gets while running.

I never ran a submerged drive before. I plan on running it on 5s or 6s depending how silly it gets while running.

Hi Johnny,

The stock 3S set-up turns the prop at 18000 rpm under load, on 5S this will be close to 30000 rpm.

Given the fact that in stock form, there's allready a lot of air drawn under the hull, which the prop turns into foam (you can hear it in the video), using 5S or 6S will make that worse, to the point where the propulsion ceases and the prop only creates foam, while the boat barely moves.

When the prop does keep it's grip, expect 'silly' performance; a boat that will try to fly, while suffering from propwalk...

My (much larger) 47" M.A.S. with it's stepped hull also draws a lot of air under the hull, but that's intentional (air having much less drag than water), initial tests with small props (40-45mm) showed no increase in speed over a certain rpm, the prop would simply loose grip and the boat slowed down.
Only after I increased the propsize to a 58 mm (2,3") coarse pitch aluminum two blade, the boat kept accelerating once it got on step.
For it's size it's still not very fast at 32 mph, but it's a scale(ish) model, powered by a 4250 800Kv outrunner on 4S (10.000 rpm under load)
Pictures and video's in my build thread: https://www.rcgroups.com/forums/show...i+Sommergibile